<template>
  <div class="div" @click="createdCode">
    <canvas id="div" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
import Vue from 'vue'
export default Vue.extend({
  props: {
    fontSizeMin: {
      type: Number,
      default: 30,
    },
    fontSizeMax: {
      type: Number,
      default: 36,
    },
    backgroundColorMin: {
      type: Number,
      default: 255,
    },
    backgroundColorMax: {
      type: Number,
      default: 255,
    },
    colorMin: {
      type: Number,
      default: 0,
    },
    colorMax: {
      type: Number,
      default: 160,
    },
    lineColorMin: {
      type: Number,
      default: 100,
    },
    lineColorMax: {
      type: Number,
      default: 255,
    },
    dotColorMin: {
      type: Number,
      default: 0,
    },
    dotColorMax: {
      type: Number,
      default: 255,
    },
    contentWidth: {
      type: Number,
      default: 120,
    },
    contentHeight: {
      type: Number,
      default: 54,
    },
  },
  data() {
    return {
      identifyCode: '',
    }
  },
  mounted() {
    this.createdCode()
  },
  methods: {
    // 生成4个随机数
    createdCode() {
      const len = 4
      const codeList = []
      const chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz01234569'
      const charsLen = chars.length
      for (let i = 0; i < len; i++) {
        codeList.push(chars.charAt(Math.floor(Math.random() * charsLen)))
      }
      this.identifyCode = codeList.join('')
      /* 子组件向父组件传递验证码 */
      this.$emit('getIdentifyCode', this.identifyCode.toLowerCase())
      // this.$emit('getIdentifyCode', this.identifyCode)
      this.drawPic()
      // console.log(this.identifyCode)
    },

    // 生成一个随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min)
    },
    // 生成一个随机的颜色
    randomColor(min, max) {
      const r = this.randomNum(min, max)
      const g = this.randomNum(min, max)
      const b = this.randomNum(min, max)
      return 'rgb(' + r + ',' + g + ',' + b + ')'
    },

    drawPic() {
      const canvas = document.getElementById('div')
      const ctx = canvas.getContext('2d')
      ctx.textBaseline = 'bottom'
      // 绘制背景
      ctx.fillStyle = this.randomColor(
        this.backgroundColorMin,
        this.backgroundColorMax
      )
      ctx.fillRect(0, 0, this.contentWidth, this.contentHeight)
      // 绘制文字
      for (let i = 0; i < this.identifyCode.length; i++) {
        this.drawText(ctx, this.identifyCode[i], i)
      }
      this.drawLine(ctx)
      this.drawDot(ctx)
    },

    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax)
      ctx.font =
        this.randomNum(this.fontSizeMin, this.fontSizeMax) + 'px SimHei'
      const x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1))
      const y = this.randomNum(this.fontSizeMax, this.contentHeight - 5)
      var deg = this.randomNum(-45, 45)
      // 修改坐标原点和旋转角度
      ctx.translate(x, y)
      ctx.rotate((deg * Math.PI) / 180)
      ctx.fillText(txt, 0, 0)
      // 恢复坐标原点和旋转角度
      ctx.rotate((-deg * Math.PI) / 180)
      ctx.translate(-x, -y)
    },

    // 绘制干扰线
    drawLine(ctx) {
      for (let i = 0; i < 5; i++) {
        ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax)
        ctx.beginPath()
        ctx.moveTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        )
        ctx.lineTo(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight)
        )
        ctx.stroke()
      }
    },

    // 绘制干扰点
    drawDot(ctx) {
      for (let i = 0; i < 80; i++) {
        ctx.fillStyle = this.randomColor(0, 255)
        ctx.beginPath()
        ctx.arc(
          this.randomNum(0, this.contentWidth),
          this.randomNum(0, this.contentHeight),
          1,
          0,
          2 * Math.PI
        )
        ctx.fill()
      }
    },
  },
})
</script>
<style scoped>
.div {
  margin: 0;
  padding: 0;
  height: 45px;
}
.div canvas {
  margin-top: 0px;
  margin-left: 0px;
  width: 120px;
  height: 45px;
}
.div canvas:hover {
  cursor: pointer;
}
</style>
